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Biomedical subjects

H L He

Publications and source records attributed to H L He.

4 recordsLinked to original sources
PubMed2005

Plasma propofol concentrations during orthotopic liver transplantation.

OBJECTIVE: The aim of this study was to investigate the changes in plasma concentrations of propofol in three phases (the paleohepatic, anhepatic, and neohepatic phases) during orthotopic liver transplantation (OLT) using target-controlled infusion (TCI). METHODS: Ten patients undergoing OLT without venovenous bypass were studied (age 29-53 years, weight 56-79 kg). After intubation, a non-hypnotic target concentration of propofol 0.5 microg ml(-1) using a Diprifusor pump (Zeneca Pharmaceuticals, Macclesfield, UK) was administered as a supplement anesthesia throughout the procedure. Plasma samples were obtained in each phase for propofol assay, respectively. Performance parameters for the Diprifusor system in each phase, the percentage median performance error (MDPE), the percentage median absolute performance error (MDAPE), and the percentage median absolute constancy error (MDACE) were evaluated. RESULTS: In all patients, measured plasma propofol concentrations were several times higher than Diprifusor values in each phase during the procedure. In nine patients, propofol concentrations in the anhepatic phase were higher than those in the paleohepatic or neohepatic phase (P < 0.05). There were no significant differences between the paleohepatic and neohepatic phases. Interindividual variation of the plasma propofol concentrations was significant (P < 0.05). Percentage median performance error of Diprifusor in each phase, as well as MDAPE, was large (>300%) and was significantly higher in the anhepatic phase (P < 0.01), whereas MDACE was relatively small and there was no significant difference between phases. CONCLUSIONS: Models used by Diprifusor are not suitable for liver transplantation patients. A further study should be performed in order to determine all pharmacokinetic parameters of propofol in these patients.

Adult↗
PubMed1999

Modeling gene expression with differential equations.

We propose a differential equation model for gene expression and provide two methods to construct the model from a set of temporal data. We model both transcription and translation by kinetic equations with feedback loops from translation products to transcription. Degradation of proteins and mRNAs is also incorporated. We study two methods to construct the model from experimental data: Minimum Weight Solutions to Linear Equations (MWSLE), which determines the regulation by solving under-determined linear equations, and Fourier Transform for Stable Systems (FTSS), which refines the model with cell cycle constraints. The results suggest that a minor set of temporal data may be sufficient to construct the model at the genome level. We also give a comprehensive discussion of other extended models: the RNA Model, the Protein Model, and the Time Delay Model.

Computational Biology↗
PubMed1992

Identification of a novel gene expressed in activated natural killer cells and T cells.

We have isolated a cDNA clone from a human activated NK cell-derived cDNA library that identifies a transcript (NK4) that is selectively expressed in lymphocytes. The expression of this transcript is increased after activation of T cells by mitogens or activation of NK cells by IL-2 (lymphokine-activated killer cells). The transcript levels demonstrated by Northern blot analysis increase by 12 h after activation, remain high for at least 48 h, and require protein synthesis for expression. Southern blot analysis of B lymphoblastoid lines derived from 18 unrelated individuals reveal variable banding patterns suggestive of polymorphism within the NK4 gene. No homology was found between the sequence of the coding region of this transcript and any sequences in the GenBank data base. Sequence homology to the U1 small nuclear RNA was found within the 3' untranslated region immediately upstream of the site of polyadenylation, suggesting a possible role for U1 in the polyadenylation process. Sequence analysis indicates the transcript would encode a protein having a mass of 27 kDa. The presence of a signal sequence and lack of a transmembrane region suggests that the protein is secreted. In addition, the protein contains an RGD sequence that may be involved in cellular adhesion. This transcript appears to encode a novel product common to the activation pathways of both NK cells and T cells.

Amino Acid Sequence↗